The objective of this project is to study structural and functional relationships in the human lung during growth, with normal aging, and, in early obstructive airways disease. Measurements of mechanical function in carefully selected postmortem human lungs include pulmonary resistance, lung elastic recoil, maximal expiratory flow rates, dynamic compliance, closing volume, and regional ventilation using radioactive xenon. Studies thus far indicate that mean values for these measurements in carefully selected lungs correspond very closely to the same measurements in age-matched live subjects. These functional measurements are correlated with detailed morphologic studies on the same lungs. These anatomical studies include bronchographic measurements of airway diameter at different levels of the bronchial tree and histologic measurements of small airway diameters, bronchial gland mass, the alveolar surface to volume ratio, and parenchymal elastin content. Approximately 100 lungs from persons 1-97 years of age have been studied and this work is continuing.